I've always enjoyed both the mechanics and backstory elements of making a character. I found the classes in D&D pretty limiting though, as archetypes go after a couple of decades of playing you run through most options.
In the end my friends and I created the Secret of Zir'An, which has a more Traveller meets Warhammer Fantasy Roleplay in reverse kind of thing. We wanted something that, after you were done with stats and skills and abilities, really gave you a framework of who your character was besides the 'I'm a first level sorcerer who's off to adventure for no reason', which is what you get from D&D nowadays.
How long on average does everyone think its worth it to spend on a character. I usually take about an hour to hour-and-a-half to fill out the character record and write a little something about them.
Marty